Method of producing a light-emitting diode

ABSTRACT

A method of separating two layers of material from one another in such a way that the two separated layers of material are essentially fully preserved. An interface between the two layers of material at which the layers of material are to be separated, or a region in the vicinity of the interface, is exposed to electromagnetic radiation through one of the two layers of material. The electromagnetic radiation is absorbed at the interface or in the region in the vicinity of the interface and the absorbed radiation energy induces a decomposition of material at the interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 10/324,848, filed Dec. 20,2002, now U.S. Pat. No. 6,740,604, which was a divisional of applicationSer. No. 09/283,907, filed Apr. 1, 1999, now U.S. Pat. No. 6,559,075,which was a continuation of International Application PCT/DE97/02261,filed Oct. 1, 1997, which designated the United States, and which wasnot published in English.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention lies in the field of semiconductor manufacture.Specifically, the invention relates to a method of producing alight-emitting diode.

The term material layers is intended here to mean both layers of asingle material and layer sequences or layer structures of differentmaterials.

The production of products from semiconductors, for example electronicand optoelectronic components, typically requires a plurality of processsteps, including the processes needed for growing semiconductor crystalsand semiconductor layers, and for selective local removal andstructuring of the layers. Many components consist in part of layersequences of non-identical semiconductor materials, which areepitaxially grown in monocrystalline form on a substrate.

As the process steps for structuring semiconductor layers or forseparating two semiconductor layers from one another, etching processesare customarily used which erode the semiconductor layers starting fromthe semiconductor surface. Such processes often take place very slowlyand require corrosive chemicals. Further, not every known semiconductormaterial system has an etching process which allows corresponding layersto be structured with tolerable outlay.

In particular, the semiconductor materials indium nitride, galliumnitride and aluminum nitride (InN, GaN and AlN) and mixed crystals oralloys thereof, which will be referred to together in the text below as“group III nitrides”, are very difficult to etch chemically. No reliablewet chemical etching process is currently available for this materialsystem. It is therefore necessary to use the technically very elaborateprocess of reactive ion etching (dry etching). However, this processallows only relatively low etching rates and requires poisonous andtoxic gases (for example boron trichloride). Because etching processesact on the surface, it is usually necessary to control the rate andduration of the etching accurately in order to reach the desired depth.

Further, for some semiconductor materials, for example and in particularfor group III nitrides, bulk crystals of them or of lattice-matchedsemiconductor materials cannot be produced, or can be produced only withgreat technical outlay. Substrates for growing such semiconductor layersare therefore only of very limited availability. For this reason it iscommon practice, in order to grow these semiconductor layers, as areplacement to use substrates of other materials which have propertiesunsatisfactory for subsequent process steps or for the operation of thecomponent. For the growth of group III nitride layers, these are, forexample, sapphire or silicon carbide substrates.

These “replacement” substrates entail problems such as unsuitable atomiclattice spacings and different coefficients of thermal expansion, whichhave detrimental effects on the material quality of the semiconductorlayers grown on them. Further, some process steps such as the knowncleavage of semiconductor layers in order to produce resonator mirrorsof laser diodes in GaAs, are difficult or even impossible with thesesubstrates.

In order to overcome these problems, various processes alternative toetching have to date been proposed for separating semiconductor layersor other layers from one another or from a problematic substrate.

In E. Yablonovitch et al., Appl. Phys. Lett. 51, 2222 (1987), U.S. Pat.No. 4,846,931, Thomas J. Gmitter and E. Yablonovitch, Jul. 11, 1989, ithas been proposed to implement AlAs sacrificial layers in the GaAs/AlAsmaterial system during the production process, which can then bedissolved using wet chemical means. This makes it possible to separatelayers or structures from the substrate. However, because of the lowlateral etching rate, this process is very time-consuming. For group IIInitrides, furthermore, there exists no wet chemical etchant.

U.S. Pat. No. 4,448,636 describes a process for removing metal filmsfrom a substrate. There, the metal film is heated by light. An organicsacrificial layer between the substrate and the metal film is vaporizedby the heat delivered and allows the metal layer to be removed. Theseorganic intermediate layers cannot be employed, in particular, in theepitaxial growth of group III nitrides.

A comparable process has been described for removing silicon dioxidelayers from gallium arsenide in Y.-F. Lu, Y. Aoyagi, Jpn. J. Appl. Phys.34, L1669 (1995). There, as well, an organic intermediate layer isheated by light absorption and the SiO₂ layer is lifted off.

Y.-F. Lu et al., Jpn. J. Appl. Phys. 33, L324 (1994) further disclosesthe separation of SiO₂ strips from a GaAs layer using an excimer laser.

German patent DE 35 08 469 C2 describes a process for structuring layersequences applied to a transparent substrate, in which the layers to bestructured are exposed to laser radiation locally through a transparentsubstrate, and this laser radiation is absorbed in the layer to bestructured.

Further, so-called laser ablation has been applied to many materialsystems in order to remove material. In this process, however, thesurface is always destructively eroded and separation in two parts thatcan be used further is not possible.

Specifically for group III nitrides, Leonard and Bedair, Appl. Phys.Lett. 68, 794 (1996) describe the etching of GaN with a laser pulseunder HCl gas and attribute it to a photochemical reaction involvinghydrochloric acid.

Morimoto, J. Electrochem. Soc. 121, 1383 (1974) and Groh et al., physicastatus solidi (a) 26, 353 (1974) describe the thermally activateddecomposition of GaN.

In Kelly et al., Appl. Phys. Lett. 69 (12), Sept. 16, 1996, p .1749-51it is shown that group III nitrides can be laser-induced to undergothermally activated composition. However, that process likewise involvesa process that acts on the surface of the semiconductor layer and, inparticular, leads to the destruction of the surface.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an improvedmethod of separating two layers of material from one another, whichovercomes the above-mentioned disadvantages of the heretofore-knowndevices and processes of this general type and which is not subject todestruction, or only slight destruction, of the free surfaces of thesemiconductor layers. The object is, in particular, to develop a processfor separating group III nitride layers from sapphire or SiC substrates.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a process for separating two layers ofmaterial from one another and substantially completely preserving eachof the two layers of material. The process comprises the followingsteps:

providing two layers of material having an interface boundary betweenthe two layers;

irradiating the interface boundary between the two layers or a region invicinity of the interface boundary with electromagnetic radiationthrough one of the two layers;

absorbing the electromagnetic radiation at the interface or in theregion in the vicinity of the interface and inducing a material at theinterface boundary to decompose; and

separating the two layers of material.

In accordance with an added feature of the invention, a sacrificiallayer is formed at the interface boundary and wherein the absorbing stepcomprises absorbing the radiation with the sacrificial layer anddecomposing the sacrificial layer.

In accordance with an additional feature of the invention, thesacrificial layer is formed of a material having an optical band gapsmaller than a band gap of one of the two layers.

In accordance with another feature of the invention, the decompositionis induced by converting an energy of the absorbed radiation into heat.

In accordance with a further feature of the invention, atemperature-sensitive sacrificial layer is formed at the boundaryinterface, and the absorbing step comprises absorbing the radiation in apart of one of the layers of material, diffusing the energy in form ofheat into the temperature-sensitive sacrificial layer, and decomposingthe sacrificial layer.

In accordance with again an added feature of the invention, thedecomposition of the interface boundary is induced by generating gas, bymeans of a chemical reaction, sublimation, or another process, at theinterface boundary with energy of the absorbed radiation.

In accordance with again an additional feature of the invention, one ofthe two layers of material is a substrate and the other of the twolayers of material is a semiconductor layer, a semiconductor layersequence, or a semiconductor layer structure, and the irradiating stepcomprises radiating the electromagnetic radiation through the substrate.Preferably, the semiconductor body is applied for mechanicalstabilization on a support material.

In accordance with again another feature of the invention, theirradiating step comprises exposing the material to one or more lightpulses. In a preferred mode, two or more coherent laser beams produce aninterference pattern in the exposure. The local radiation intensity isthereby increased.

In accordance with again a further feature of the invention, thesemiconductor body consists at least partially of GaN, AlN, InN, mixedcrystals thereof, layer sequences, layer structures, and componentstructures thereof. Where the sacrificial layer is provided, it consistsat least partially of a GaN, AlN, InN, or mixed crystals thereof.

With the above and other objects in view there is also provided, inaccordance with the invention, a process for laterally structuring asemiconductor layer or a semiconductor layer sequence disposed on asubstrate. The novel process comprises the following steps:

providing a substrate and a body of semiconductor material consistingessentially of at least one group III nitride material on the substrate,with an interface formed between the substrate and the semiconductormaterial;

The invention thus proposes to separate the two materials in that,through one of the two layers of material, the interface, or a region inthe vicinity of the interface between the two layers, is exposed toelectromagnetic radiation, and that a layer of material at or inproximity to the interface is decomposed by absorption of the radiation.

This process is an alternative to wet and dry chemical etching processesas are used in semiconductor technology for structuring and producingindividual layers and components. It differs from them essentially inthat it acts directly on an internal region at the interface between thetwo layers and not on the free surface. This makes it possible, amongstother things, to produce the desired structuring depth directly insteadof, for example, defining it by accurately setting the duration and rateof the etching. In the method according to the invention, in addition,there is no destruction of one of the two layers of material. This leadsto a novel possibility for detaching layer systems from one another orfrom the substrate. Cantilevered components or layers have advantages infurther process steps; they are suitable, for example, as substrates forhomoepitaxy without the problems of lattice mismatching and thedifferences in the coefficients of thermal expansion, or to produceoptical components (laser diodes) through the possibility of cleavageirrespective of the substrate cleavability. The transfer of layers,layer systems and components of group III nitride materials to othersubstrates permits compatibility and integration of group III nitrideswith other technologically relevant semiconductor systems such assilicon.

The process makes it possible to separate layers of a layer/substratesystem through direct highly local action on internal interfaces orregions in proximity to interfaces. In general, the process describedhere can be applied to material systems in which the interface to beseparated can be reached with electromagnetic radiation, in particularwith light, the radiation is absorbed by a material at this interface,and in which material in proximity to the interface can be decomposed bythe absorption of light or light pulses. The process is facilitated ifat least one decomposition product is in the form of gas. Examples ofsuitable semiconductor materials for this process include group IIInitrides, oxide materials and Si₃N₄.

Optoelectronic components such as light-emitting diodes andsemiconductor lasers and electronic components such as transistors,diodes, surface acoustic wave components are typically produced in largenumbers on a single substrate. In this case, the described process oflight-induced structuring can be used for separating the individualcomponents. The separation of the components from the substrate may, asmentioned above, take place through the decomposition of a sacrificiallayer which needs to be introduced during the fabrication process underor over the surface to be separated. Thin InGaN layers are especiallysuitable for this because of their comparatively small band gap andtheir chemical stability.

The production of freestanding layers and layer sequences makes itpossible to transfer layers of group III nitrides to other substrates(for example silicon) which may differ greatly in terms of theirstructural, mechanical and thermal properties from those of group IIInitrides. The procedure makes it possible to combine light-emittingdiodes and semiconductor lasers made of group III nitrides withconventional support materials for the production of flat displayscreens or the integration of such components in circuits and integratedcircuitry. Cantilevered layer structures can also be used as opticalwaveguides and optical couplers. If this is structured with adiffraction grating, the light can be coupled in through the grating.Layers of specific thickness can also be employed as optical filters.

By means of exposure through a mask, exposure with coherent light beamscombined with interference patterning, holography, or serial orsimultaneous exposure of various selected locations, lateral structuringof one of the layers of material can be produced.

The essential steps in the method according to the invention are asfollows:

-   (i) identification, selection or production of an interface to be    separated in the desired layer system, which can be reached by the    radiation to be used for separation;-   (ii) identification of a material, or incorporation of a material as    a sacrificial layer at the interface, which material absorbs the    incident light; or-   (iii) identification or incorporation of a material as a sacrificial    layer in proximity to the interface, which material can be made to    decompose by the absorbed light or by the energy resulting    therefrom, and produces a product in gas form in sufficient quantity    during the decomposition; and-   (iv) exposure to radiation of a selected wavelength and intensity,    so that the radiation is predominantly absorbed by the interface to    be separated or by the sacrificial layer, and thereby stimulates the    decomposition reaction, in the case of transparent substrates it    also being possible for the interface or sacrificial layer to be    exposed through the substrate.

The method according to the invention is, in particular, also usable forstructuring semiconductor layers consisting of group III nitrides which,for example, are applied to SiC or sapphire substrates.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a method of producing a light-emitting diode, it is nevertheless notintended to be limited to the details shown, since various modificationsand structural changes may be made therein without departing from thespirit of the invention and within the scope and range of equivalents ofthe claims.

The construction and process of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial schematic sectional side view of a first exemplaryembodiment of the invention;

FIG. 2 is a partial schematic sectional side view of a second exemplaryembodiment of the invention;

FIG. 3 is a partial schematic sectional side view of a third exemplaryembodiment of the invention;

FIG. 4 is a partial schematic sectional side view of a fourth exemplaryembodiment of the invention;

FIG. 5 is a partial schematic sectional side view of a fifth exemplaryembodiment of the invention;

FIG. 6 is a partial schematic sectional side view of a sixth exemplaryembodiment of the invention;

FIG. 7 is a partial schematic sectional side view of a seventh exemplaryembodiment of the invention;

FIG. 8 is a partial schematic sectional side view of a eighth exemplaryembodiment of the invention; and

FIG. 9 is a partial schematic sectional side view of a ninth exemplaryembodiment of the invention.

Equivalent or functional equivalent components and features in thefigures are identified with the same reference symbol throughout.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first,particularly, to FIG. 1 thereof, there is seen a first embodiment withan interface of a layer system made up of a first semiconductor layer 2and of a second semiconductor layer 4. The layer system is exposed to alaser beam 1 through the first semiconductor layer 2. The light isstrongly absorbed in the material of the second semiconductor layer 4.The first semiconductor layer 2 is transparent to the laser beam 1.

The energy absorbed in the second semiconductor layer 4, predominantlyin proximity to the interface between the two semiconductor layers 2, 4,induces for example decomposition of the semiconductor material of thesecond semiconductor layer 4 in that region. This brings about theseparation of the two semiconductor layers 2 and 4. Examples of possibledecomposition mechanisms include sublimation or chemical reactions. Thedecomposition may in this case be both thermally and photochemicallyinitiated. The separation is, in particular, reinforced if products ingas form are produced during the decomposition.

It is, however, also possible for the energy absorbed in thesemiconductor layer 4 to diffuse into the semiconductor material 2 andfor the decomposition to take place there. The relative thickness of thetwo semiconductor materials may in this case vary greatly. The equalthickness measurements of FIG. 1 are not necessary. In that regard, thefigures of the drawings are not necessarily drawn to scale.

One much-used process of producing semiconductor materials is growth onsubstrates. In terms of the process presented here, the distinctionbetween substrate and semiconductor material is irrelevant. Onepossibility is for the semiconductor layers 2, 4 to be grown on asubstrate and for the separation to take place at the interface betweenthe semiconductor layers 2, 4.

In the illustrative embodiment in FIG. 2, a semiconductor layer 4 isseparated from a substrate 6. In order to do this, the semiconductorlayer 4 is exposed to light 1 through the substrate 6 and the radiationenergy is absorbed in the material of the semiconductor layer 4.Depending on the absorption properties, it may however also be possibleto expose the interface through the semiconductor layer 4 so that thesubstrate 6 absorbs the light energy. As already presented above, it isnot however necessary for the decomposition to take place in theabsorbing part of the structure, and the energy may where appropriatealso diffuse into the other part and bring about the decompositionthere.

The semiconductor layers 2, 4 may either each be homogeneous layers ofone semiconductor, or consist of layer sequences of differentsemiconductors, as indicated with reference to the example of thesemiconductor layer 4 in FIG. 3. These layer sequences may alreadycontain an actual component preprocessed or fully processed, even in theform of an integrated electronic or optoelectronic circuit. All thesestructures are in the context of the application to be interpreted assemiconductor layers.

In order to improve and deliberately affect the absorption of the lightat the interface to be separated, in accordance with the fourthillustrative embodiment according to FIG. 4 a special absorbing layer 8may be interposed between a first semiconductor layer 2 and a secondsemiconductor layer 4, or between the substrate 6 and the semiconductorlayer 4 (cf. FIG. 2). The absorbing layer 8, for example a semiconductorlayer, has for example an optical band gap which is smaller than that ofthe surrounding materials. The layer 8 can then itself be decomposed andtherefore act as a sacrificial layer. It is, however, also possible forthe absorbed energy to diffuse and lead to decomposition and separationin proximity to the layer 8.

It is also possible for the energy to be absorbed in the semiconductorlayer 4 but for the latter to be too stable to become decomposed. Inthis case, the layer 8 may be selected in such a way that it decomposesparticularly readily, and thus again functions as a sacrificial layer.One particular advantage of the process described here is that the layer8 may be crystalline and lattice-matched.

The electromagnetic radiation must be selected in such a way that it canreach the interface to be separated and be absorbed sufficiently there.This can be done in the simplest case by illumination using a lamp, ifappropriate after filtering. If the photon flux which this provides isinsufficient, the illumination may also be carried out using a suitablelaser.

Particularly in the case of thermal decomposition, the heat may diffuserapidly out of the region to be decomposed on account of the thermalconductivity of the materials. It may therefore be necessary to deliverthe light energy in the form of very short light pulses, in ordernevertheless to reach the temperature needed for the decomposition.

The process described here may also be used for lateral structuring.This can be carried out using various procedures. A focused light beamcan be employed for sequentially exposing spatially separate points ofthe material and for bringing about the decomposition. As shown in theillustrative embodiment in FIG. 5, it is possible to use an exposuremask 10 through which selected areas of the sample can be removed.

Likewise, in accordance with the illustrative embodiment in FIG. 6,exposure using holographic process is possible (for example exposurewith an interference grating), in which the interference effects areutilized through simultaneous exposure to more than one coherent beam.

The part separated by the interfacial decomposition may be very thin orsmall, and therefore mechanically unstable and difficult to process. Itis possible to apply this part according to the illustrative embodimentin FIG. 7 before or after the separation, for example using adhesive 12,to a new support material 14. This is represented by way of example forthe case of fixing before the interfacial decomposition in FIG. 7.

After the separation, a thin semiconductor layer 4, separated from thesubstrate 6, is then available on the support material.

Particularly advantageously, the method according to the invention maybe used for the production of layer sequences 4 or complete componentstructures of electronic or optoelectronic components, which are formedon nonconducting substrates. In these cases, it is often difficult, inaddition to the electrical contact 16 arranged in each case on the otherside of the layer sequence 4 or component structure from the substrate,to arrange an electrical contact on a semiconductor layer arranged inproximity to the substrate. In order to do this, complicated etchingprocesses and the formation of mesa structures are usually necessary.With the process described here, according to the illustrativeembodiment in FIG. 8 it is possible to detach layer sequences 4 orcomplete component structures from nonconducting substrates. The sidesof the layer sequences 4 or component structures which are now free butpreviously faced the substrate are now readily accessible for electricalcontacts 18.

The way in which this process is implemented depends on the materialsystem. A preferred embodiment for semiconductor materials uses amaterial on the interface to be separated with a smaller band gap thanall other layers or materials on one side of the interface. Forexposure, a radiation wavelength is selected at which the radiation canpenetrate as far as the interface, and which is absorbed by the materialwith smaller band gap. Decomposition in this or a neighboring materialmust thereby be inducible.

This process is particularly suitable for layers or layer systems ofgroup III nitrides since this group of materials has some physicalproperties particularly advantageous for this process. Firstly, it ispossible to heat group III nitrides above their decompositiontemperature in a spatially delimited and controlled way through theabsorption of individual light pulses. At the temperatures produced bythe absorption of light pulses, the decomposition of the nitrides andthe formation of nitrogen gas is initiated (600° C.-1800° C., dependingon the composition of the nitrides). Secondly, the described procedureis assisted by the fact that the melting points of group III nitridesare far higher than the decomposition temperatures, so that during theabsorption of intense light pulses the layers and components do notbecome damaged by melting. Thirdly, these semiconductor materials areespecially suitable for optical processes since, as a function of thewavelength of the light, they have a well-defined sharp threshold, adirect band gap, at which they change from transparent to fullyabsorbing. Further, the wavelength from which the absorption starts canbe varied using mixed crystals of the nitrides (InGaN and AlGaN) over awide spectral range (band gaps: InN 1.9 eV, GaN 3.4 eV, AlN 6.2 eV). Inaddition, group III nitrides are often produced on sapphire substrateswhich are transparent throughout the optical and ultraviolet range. Thiseven makes it possible to expose the layers through the substrate.

If the decomposition is thermally activated, it is important for it tobe possible for the resultant heat to be concentrated onto the interfaceor the sacrificial layer, on the one hand in order to minimize therequired incident intensity, and on the other hand in order to precludethe possibility of undesired effects on the surrounding material. Sincethe photogenerated quantity of heat is rapidly dissipated by the thermalconductivity of the materials out of the hot volumes, the requisitetemperature must be produced in a very short time. This can be doneusing short laser pulses. For typical thermal conductivities of groupIII nitrides, the absorbed energy can be concentrated through the use oflaser pulses with a period of 1 ns to 10 ns onto the penetration depthof the absorbed light or the thickness of the sacrificial layer. For thestructuring and decomposition of group III nitrides, one suitableexample is a “Q-switched” pulsed Nd:YAG laser.

As a specific embodiment for the photoinduced decomposition of thematerials GaN and InGaN (band gaps between 1.9 and 3.4 eV), the thirdharmonic laser line of an Nd:YAG laser may be used. This laser line isproduced, for example, using a nonlinear optical crystal and has awavelength of 355 nm (3.5 eV). GaN and InGaN layers absorb these lightpulses and can be made to decompose. AlGaN layers and the customarilyused sapphire substrate are transparent to this wavelength.

Cantilevered GaN and InGaN layers can be produced directly bydecomposition of the substrate/layer interface. AlGaN layers andcomponents can be detached from the substrate by photoinduceddecomposition of thin GaN or InGan sacrificial layers. FIG. 7schematically shows the way of separating a GaN layer 4 from a sapphiresubstrate 6, polished on both sides. The interface between the GaN andthe sapphire is exposed through the substrate to a single laser pulse ofwavelength 355 nm. The laser radiation is absorbed by the GaN inproximity to the interface down to a depth of about 100 nm, as a resultof which the interface becomes heated. If temperatures in excess of 850°C. are reached, the GaN starts to decompose with the formation ofnitrogen gas. For pulse energies of more than about 0.2 J/cm², theenergy density is sufficient for complete decomposition at the boundarybetween the substrate 6 and the GaN layer 4, as a result of which thebond between the substrate 6 and GaN layer 4 is separated in the exposedarea. In order to stabilize the cantilevered layer, the sample may bebonded using a resin or wax 12 to a support wafer or sheet 14 via theside of the layer prior to the exposure. If the GaN layer 4 is separatedfrom the substrate 6 by the decomposition reaction, the sapphiresubstrate 6 can be lifted off and the GaN layer 4 remains behind on thesupport wafer or sheet 14. The wax or resin can then be dissolved inacetone and the GaN layer remains behind as a cantilevered layer.

When structuring GaN layers by exposing the interface through a sapphiresubstrate, GaN structures with nonvertical, that is to say oblique sidefaces can be produced, which, as FIG. 9 shows, propagate from thedecomposition site. This process can, for example, be used to producestructures 20 with a pointed or pyramidal design if the lateral width ofthe interference grating or the mask is matched to the layer thickness.This process also helps the production of cantilevered layers.

Various components made of group III nitrides can be structured usingthe described procedures. The fabrication of periodic line gratings andsurface structures by exposure with an interference grating canadvantageously be used to produce Bragg reflectors and distributedfeedback lasers based on group III nitrides. It is also possible toobtain optical dispersion gratings, which if appropriate may also beused for transmitted light, through variation of the thickness of thelayer by structuring with an interference grating. Pyramidal structuresof AlN and AlGaN can, because of their negative electron affinity, beused as cold cathode emitters, for example, in flat display screens.

1. A method of producing a light emitting diode or a laser diode, themethod which comprises: providing a growth substrate and a semiconductorbody selected from the group consisting of a semiconductor layer, asemiconductor layer sequence, and a semiconductor layer structure grownon the substrate; irradiating an interface boundary between thesubstrate and the semiconductor body or a region in a vicinity of theinterface boundary with electromagnetic radiation; absorbing theelectromagnetic radiation at the interface boundary or in the vicinityof the interface boundary and inducing a material at the interfaceboundary to decompose; and separating the substrate from thesemiconductor body.
 2. The method according to claim 1, which furthercomprises providing a sacrificial layer at the interface boundary andwherein the absorbing step comprises absorbing the radiation with thesacrificial layer and decomposing the sacrificial layer.
 3. The methodaccording to claim 2, wherein the sacrificial layer is formed of amaterial having an optical band gap smaller than a band gap of one ofthe two layers.
 4. The method according to claim 1, wherein theabsorbing step comprises inducing the decomposition by converting anenergy of the absorbed radiation into heat.
 5. The method according toclaim 1, which further comprises forming a temperature-sensitivesacrificial layer at the boundary interface, and wherein the absorbingstep comprises absorbing the radiation in a part of the substrate or thesemiconductor body, diffusing the energy in form of heat into thetemperature-sensitive sacrificial layer, and decomposing the sacrificiallayer.
 6. The method according to claim 1, wherein the absorbing stepcomprises inducing a decomposition of the interface boundary bygenerating gas at the interface boundary with energy of the absorbedradiation.
 7. The method according to claim 6, wherein the step ofgenerating the gas comprises inducing a process selected from the groupconsisting of chemical reactions and sublimation.
 8. The methodaccording to claim 1, which comprises applying the semiconductor bodyfor mechanical stabilization on a support material.
 9. The methodaccording to claim 1, wherein the irradiating step comprises exposingthe material to one or more light pulses.
 10. The method according toclaim 1, wherein the irradiating step comprises irradiating with two ormore coherent laser beams, producing an interference pattern in theexposure, and increasing a local light intensity.
 11. The methodaccording to claim 8, wherein the semiconductor body consists at leastpartially of a material selected from the group consisting of GaN, AlN,InN, mixed crystals thereof, layer sequence, layer structures, andcomponent structures thereof.
 12. The method according to claim 2,wherein the sacrificial layer consists at least partially of a nitridematerial selected from the group consisting of GaN, AlN, InN, and mixedcrystals thereof.
 13. The method according to claim 1, wherein theirradiating step comprises exposing the interface boundary between thesubstrate and the semiconductor body or the region in vicinity of theinterface boundary to one or more light pulses.
 14. The method accordingto claim 1, wherein the irradiating step comprises irradiating with twoor more coherent laser beams, producing an interference pattern in theexposure, and increasing a local light intensity.
 15. The methodaccording to claim 1, wherein the substrate consists essentially of amaterial selected from the group consisting of sapphire, LiAlO₂, LiGaO₂,MgAl₂O₄, ScAlMgO₄, and SiC.
 16. The method according to claim 15,wherein the substrate is a sapphire substrate and the semiconductor bodyincludes a layer of a Ga compound selected from the group consisting ofGaN and In_(x)Ga_(1-x)N, and the irradiating step comprises separatingthe semiconductor body from the sapphire substrate by exposing throughthe substrate with a third harmonic of a Nd:YAG laser at a wavelength of355 nm.
 17. The method according to claim 16, which comprises pulsingthe Nd:YAG with a Q-switch.